atmosphere

Article Mapping Climate Change, Natural Hazards and Tokyo’s Built Heritage

Peter Brimblecombe 1,2,3,* , Mikiko Hayashi 4 and Yoko Futagami 5

1 School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong 2 Department of Marine Environment and Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan 3 Aerosol Science Research Center, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan 4 Center for Conservation Science, National Institutes for Cultural Heritage Tokyo National Research Institute for Cultural Properties, Tokyo 110-8713, Japan; [email protected] 5 Department of Art Research, Archives and Information Systems, Tokyo National Research Institute for Cultural Properties, Tokyo 110-8713, Japan; [email protected] * Correspondence: [email protected]



Received: 26 May 2020; Accepted: 24 June 2020; Published: 28 June 2020


Abstract: Although climate change is well recognised as an important issue in Japan, there has been little interest from scientists or the public on the potential threat it poses to heritage. The present study maps the impact of emerging pressures on museums and historic buildings in the Tokyo Area. We examine a context to the threat in terms of fluctuating levels of visitors as a response to environmental issues, from SARS and COVID-19, through to earthquakes. GIS mapping allows a range of natural and human-induced hazards to be expressed as the spatial spread of risk. Temperature is increasing and Tokyo has a heat island which makes the city hotter than its surroundings. This adds to the effects of climate change. Temperature increases and a decline in relative humidity alter the potential for mould growth and change insect life cycles. The region is vulnerable to sea level rise, but flooding is also a likely outcome of increasingly intense falls of rain, especially during typhoons. Reclamation has raised the risk of liquefaction during earthquakes that are relatively frequent in Japan. Earthquakes cause structural damage and fires after the rupture of gas pipelines and collapse of electricity pylons. Fires from lightning strikes might also increase in a future Tokyo. These are especially relevant, as many Japanese heritage sites use wood for building materials. In parallel, more natural landscapes of the region are also affected by a changing climate. The shifting seasons already mean the earlier arrival of the cherry blossom and a later arrival of autumn colours and a lack of winter snow. The mapping exercise should highlight the spatial distribution of risk and the way it is likely to change, so it can contribute to longer term heritage management plans.

Keywords: earthquakes; fire; floods; historic sites; landslides; museums; insects; sea level rise; typhoons; visitors

1. Introduction Our heritage is under threat. The need to protect Japanese tangible heritage from disasters has been addressed by government funding increases: JPY 2905 million in 2019, to JPY 3907 million in 2020. While natural hazards are well recognised issues in Japan and climate science is strong, there has been relatively little interest there from scientists or the public on the potential threat a changing climate poses on heritage, especially in the way they alter the frequency of meteorologically driven hazards. The present study maps the impact of external pressures on museums, historic buildings such as temples and shrines in the Tokyo Area. This is one of the most populous metropolitan areas in the world, which includes several prefectures of the Kanto¯ Region of Japan, as well as Yamanashi

Atmosphere 2020, 11, 680; doi:10.3390/atmos11070680 www.mdpi.com/journal/atmosphere Atmosphere 2020, 11, 680 2 of 18 meteorologically driven hazards. The present study maps the impact of external pressures on museums, historic buildings such as temples and shrines in the Tokyo Area. This is one of the most populousAtmosphere 2020 metropolitan, 11, 680 areas in the world, which includes several prefectures of the Kantō Region2 of 16 of Japan, as well as Yamanashi Prefecture. The Tokyo Metropolis is elongated from east to west, stretchingPrefecture. from The Tokyomountains Metropolis which isstand elongated in the from west east to toTokyo west, Bay stretching to islands from scattered mountains over which the Pacificstand inOcean; the west although to Tokyo in this Bay study to islands islands scattered are excluded, over the yet Pacific it still Ocean; covers althoughan area of in some this study1790 squareislands kilometres. are excluded, The yet Japan it still Meteorological covers an area Agency of some (JMA) 1790 square places kilometres. Tokyo in Thethe JapanEJP climate Meteorological zone (PacificAgency (JMA)side of places eastern Tokyo Japan), in the with EJP hot climate and humi zoned (Pacific summers side and of eastern cold winter Japan),s. In with winter, hot and the humid wind fromsummers the Siberian and cold continent winters. causes In winter, heavy the snow wind on from the the Sea Siberian of Japan continent side, but causes when heavythe air snow crosses on thethe mountains Sea of Japan to side, Tokyo but and when reaches the air the crosses Pacific the side mountains to Tokyo, to it Tokyo becomes and dry reaches air. The the Pacificwinter sideis the to driestTokyo, season, it becomes thus drythe air.season The is winter sunny is and the driestfairly season,mild, but thus the the city season experiences is sunny hot, and humid fairly mild,and rainybut the summers. city experiences hot, humid and rainy summers. JapanJapan is is an an island island country country in in East East Asia Asia (Fig (Figureure 11a)a) andand Tokyo,Tokyo, excludingexcluding islands,islands, isis locatedlocated between 35° 30’ 05” to 35° 53’ 54” North latitude and 138° 56’ 35” to 139° 55’ 07” East Longitude between 35◦30005” to 35◦53054” North latitude and 138◦56035” to 139◦55007” East Longitude (Figure2a). (FigureThe topography 2a). The graduallytopography decreases gradually in elevation decreases from in elevation the western from mountains the western to the mountains alluvial lowlands, to the alluvialending atlowlands, Tokyo Bay ending (Figure at Tokyo1c). The Bay terrain (Figure can 1c). be The regarded terrain as can defined be regarded by the as Tamagawa defined by River the Tamagawacatchment, andRiver the catchment, geographical and characteristics the geographical are completely characteristics different are betweencompletely east different and west, between with the eastboundary and west, near with Ome City,the boundary the estuary near settlement Ome City, in the the Kant estuaryo¯ Mountains. settlement There in the are Kant accurateō Mountains. 5 m-mesh Theredata as are a quantitative accurate 5 representationm-mesh data ofas terraina quantitati withinve the representation Digital Elevation of terrain Model (DEM)within providedthe Digital by Elevationthe Geospatial Model Information (DEM) provided Authority by the of JapanGeospatial [1]. Information Authority of Japan [1].

FigureFigure 1. ((aa)) Japan’s Japan’s position in East Asia.Asia. ( (bb)) Tokyo’s positionposition inin Japan.Japan. Source: Source: National National Land Land NumericalNumerical Information Information (https://nlftp.mlit.go.jp/ (https://nlftp.mlit.go.jp/[2][2]) (c ()c )Topography Topography of of the the Tokyo Tokyo region region discussed discussed in in this paper, with a white line denoting the boundary of the Tokyo Area. this paper, with a white line denoting the boundary of the Tokyo Area. Tokyo, as a major city with a lengthy history, has a great wealth of heritage. There are numerous historic buildings and sites shrines, temples and great buildings, perhaps some favourites being: (i) Asakusa Shrine, (ii) Tog¯ u¯ Palace, (iii) Tokyo Station, (iv) Senso-ji¯ Niten-mon, (v) Nezu Shrine, (vi) Enyuu-ji Temple, (vii) Former Iwasaki House, (viii) Eitai Bridge, (ix) Shofuku-ji Temple Jizod¯ o.¯ Add to this many historic buildings; these marked as 83 points in pink (Figure2a,b) and all of them are designated buildings and structures as National Treasure or Important Cultural Properties. Tokyo has hundreds of museums and galleries, some of the favourites being: (i) Tokyo National Museum, (ii) Edo-Tokyo Museum, (iii) Ghibli Museum, (iv) Nezu Museum, (v) Hara Museum of Contemporary Art, (vi) Mori Art Museum, (vii) Tokyo Metropolitan Art Museum, (viii) National Museum of Western Art, and (ix) the National Museum of Emerging Science and Innovation. Museums are marked as 232 points in green (Figure2a,c). Maps of heritage and the risk imposed by climate change are often seen as important tools for the strategic management of heritage, e.g., [3,4], with some at a national or regional level [5–8]. Among a few examples of Japanese studies in this field, [9,10] integrated a database of the nationally designated cultural properties and a map of the active faults with GIS to estimate the seismic risk of each property. Difficulties in such mapping involve the problem of scaling because data are typically collected at national or regional levels rather than at city scale. It is also problematic to tune the data, often collected for other purposes, to heritage; e.g., seismic risk is defined for buildings in general, not heritage, or that meteorological information is collected for many purposes, so the risks imposed on heritage requires considering the notion of heritage climate [3,11]. Special threats to the region are flooding and the increased pressures that climate change may present in terms of both river and sea floods [12,13] and the failure of sea defences [14]. As Tokyo is a coastal city, sea level rise makes low lying areas additionally vulnerable to increased flooding, Atmosphere 2020, 11, 680 3 of 16 with Estaban et al. [15], arguing that “The combined effect of an increase in typhoon intensity and sea level rise could pose significant challenges to coastal defences around Tokyo Bar around the turn of the twenty-first century.” There are also risks from earthquakes, which are regularly mapped in the city as this affects a range of issues in addition to the threat to built heritage, e.g., real estate prices [16]. The Bureau of City Planning, Tokyo Metropolitan Government maps earthquake threat in their regional risk measurement survey on earthquakes, but it is also the subject of damage forecasts. Although air pollution and acid rain represent threats, they are not treated in this paper. Tokyo has worked hard to improve its air quality [17] and the study of acid rain has a long history in Japan [18], so despite Atmosphereconcerns 2020 about, 11,the 680 high level of threat especially from Chinese emissions [19] these have been much3 of 18 reduced in the current decade [20].

Figure 2. Location of (a) Historic buildings (pink) and museums (green) in Tokyo, (b) major historic Figurebuildings 2. Location and (c) museums of (a) Historic in central buildings Tokyo. (pink) Note: and Source: museums National (green) Land in Tokyo, Numerical (b) major Information historic buildings(https://nlftp.mlit.go.jp and (c) museums/ [2]). in central Tokyo. Note: Source: National Land Numerical Information 2. Materials(https://nlftp.mlit.go.jp/ and Methods [2]).

Tokyo,This study as usesa major data city on climate with a and lengthy natural history, hazards has relevant a great to looking wealth at of long heritage. term pressures There are on numerousbuilt heritage historic in the Tokyobuildings area. and In addition sites shrines, to a range temples of research and articles, great webuildings, make use perhaps of government some favouritesand municipal being: reports (i) Asakusa to assess Shrine, the magnitude (ii) Tōgū Palace, of the threat (iii) Tokyo from aStation, changing (iv) environment. Sensō-ji Niten-mon, A range (v) of Nezuclimate Shrine, projections (vi) Enyuu-ji available Temple, from the (vii) Japanese Former Meteorological Iwasaki House, Agency (viii) Eitai [21] areBridge, especially (ix) Shofuku-ji useful in Templeestimating Jizō likelydō. Add future to this change. many Geographic historic buildings; information these system marked (GIS) as allows83 points the in threat pink to (Figure be mapped. 2a,b) and allWe of used them the are software designated QGIS, buildings originally and Quantumstructures GIS as ,National which allows Treasure users or toImportant analyse Cultural and edit Properties.spatial information Tokyo has in multiplehundreds raster of museums formats andand asgall vectoreries, data;some which of the can favourites be stored being: as either (i) Tokyo point, National Museum, (ii) Edo-Tokyo Museum, (iii) Ghibli Museum, (iv) Nezu Museum, (v) Hara Museum of Contemporary Art, (vi) Mori Art Museum, (vii) Tokyo Metropolitan Art Museum, (viii) National Museum of Western Art, and (ix) the National Museum of Emerging Science and Innovation. Museums are marked as 232 points in green (Figure 2a,c). Maps of heritage and the risk imposed by climate change are often seen as important tools for the strategic management of heritage, e.g., [3,4], with some at a national or regional level [5–8]. Among a few examples of Japanese studies in this field, [9,10] integrated a database of the nationally designated cultural properties and a map of the active faults with GIS to estimate the seismic risk of each property. Difficulties in such mapping involve the problem of scaling because data are typically collected at national or regional levels rather than at city scale. It is also problematic to tune the data, often collected for other purposes, to heritage; e.g., seismic risk is defined for buildings in general, not

Atmosphere 2020, 11, 680 4 of 16 line, or polygon features. We particularly adopted 3.6 Noosa developed by the QGIS community. The software provides viewing, editing and analysis capability to overlap a range of natural hazards in the area and their changes over time. Vector data of points and areas, such as the location of built heritage (historical sources and museums), maps of Tokyo, the area of inundation by flooding and area of potential sediment disasters, were obtained from the National Land Numerical Information Download Service [2]. Areas of inundation are calculated for each river under designated storm impacts. Where vector data of point and area data were not available, we have resorted to simple counts from manually overlapped data.

3. Results Pressures on our heritage are much discussed, and the impact of external local and global events is clear from Figure3, where the numbers of foreign visitors to Japan are plotted. Pressures from epidemics, financial collapse and geophysical events cause fluctuating visitor numbers. The most recent crisis of COVID-19 has had a special impact on the heritage sector, where it has greatly affected visitor numbers and the attendant loss of income, though in some cases the most fragile sites experienced a welcomeAtmosphere respite2020, 11, from680 heavy flows, allowing natural sites to recover a little [22]. There will also5 of be 18 problems with the subsequent cleaning of the viral contamination from properties and interior surfaces.

Figure 3. International visitors to Japan from Japan National Tourism Organization. Figure 3. International visitors to Japan from Japan National Tourism Organization. 3.1. Temperature and Urban Heat Island

3.1. Temperature and is theUrban best Heat understood Island parameter under a changing climate; likely to be affected through the addition of radiatively active gases to the atmosphere. Globally, the temperature is likely Temperature is the best understood parameter under a changing climate; likely to be affected to have increased by about 0.8 C through the 20th century. The Intergovernmental Panel on Climate through the addition of radiatively◦ active gases to the atmosphere. Globally, the temperature is Change (IPCC) Fifth Assessment Report suggests that surface temperature will rise a further 0.3 to 1.7 C likely to have increased by about 0.8 °C through the 20th century. The Intergovernmental Panel◦ on during the current century. In Japan from 1931 to 2017, the average temperature in Tokyo increased Climate Change (IPCC) Fifth Assessment Report suggests that surface temperature will rise a further at a rate of 3.2 C/century [23]. Projecting the regional climate of Eastern Japan between the periods 0.3 to 1.7 °C during◦ the current century. In Japan from 1931 to 2017, the average temperature in 1980–1999 and 2076–2095 suggests that the annual mean temperature in Tokyo, where there is a strong Tokyo increased at a rate of 3.2 °C/century [23]. Projecting the regional climate of Eastern Japan heat island, will increase by more than 3 C in almost a century. between the periods 1980–1999 and 2076–2095◦ suggests that the annual mean temperature in In recent years, high temperatures in summer have been noted in large cities such as Tokyo, Tokyo, where there is a strong heat island, will increase by more than 3 °C in almost a century. and public interest has been engaged by the added contribution the urban heat island makes to In recent years, high temperatures in summer have been noted in large cities such as Tokyo, the increase in the number of heat stroke patients. The annual mean temperature in central Tokyo and public interest has been engaged by the added contribution the urban heat island makes to the has increased about 3.2 C/century, which is 4.4 times faster than the global mean temperature increase in the number of◦ heat stroke patients. The annual mean temperature in central Tokyo has (0.73 C/century) and 2.1 times faster than the Japanese mean temperature of 1.21 C/century (JMA, increased◦ about 3.2 °C/century, which is 4.4 times faster than the global mean ◦temperature (0.73 2019). These increases are partly due to the development of the urban heat island. The current trends °C/century) and 2.1 times faster than the Japanese mean temperature of 1.21 °C/century (JMA, for this effect, studied by Lee et al. [24], suggest that the summer heat island in Tokyo is increasing 2019). These increases are partly due to the development of the urban heat island. The current at 0.85 C/century, while Manila, Seoul and Mumbai were slower, at 0.15, 0.2 and 0.36 C/century, trends ◦for this effect, studied by Lee et al. [24], suggest that the summer heat island ◦in Tokyo is respectively. The heat island clearly substantially adds to the effect of greenhouse warming. The speed increasing at 0.85 °C/century, while Manila, Seoul and Mumbai were slower, at 0.15, 0.2 and 0.36 °C/century, respectively. The heat island clearly substantially adds to the effect of greenhouse warming. The speed of temperature change in Tokyo has drawn popular comment [25] and the urban heat island is generally seen to arise from the decrease in green and water areas, the increase in ground covered with asphalt and concrete, the increase in heat (exhaust heat) generated from cars and buildings and the poor ventilation by wind in the street canyons [26]. Rising temperatures in summer have been a particular problem, because the heat island has helped reduced the comfort of urban life and affected human health. Urban influences are recognised, not only in the production of the heat island, but in other climate effects such as: urban rainfall, wind circulation, number of fog days, relative humidity, etc. [27,28]. These have impact not only human health, but also materials and the management of built heritage. Although Tokyo has a strong heat island, there are potentials to mitigate this, through the urban greening of buildings or increasing the area of open water in central Tokyo [29,30]. Temperature increases and a decline in relative humidity alter the potential for mould growth and change insect life cycles. The total number of hours with above 30 °C are shown in Figure 4. This will affect comfort within naturally ventilated buildings and put more pressure on the cooling systems in museum environments. It can also affect mould growth when accompanied by humid conditions, and will favour insect infestations. In Japan, the overwintering survival of insects has increased along with earlier appearances in the spring, an increase in the number of generations each year, lengthening of the reproductive season, etc. However, insects can also be susceptible to

Atmosphere 2020, 11, 680 5 of 16 of temperature change in Tokyo has drawn popular comment [25] and the urban heat island is generally seen to arise from the decrease in green and water areas, the increase in ground covered with asphalt and concrete, the increase in heat (exhaust heat) generated from cars and buildings and the poor ventilation by wind in the street canyons [26]. Rising temperatures in summer have been a particular problem, because the heat island has helped reduced the comfort of urban life and affected human health. Urban influences are recognised, not only in the production of the heat island, but in other climate effects such as: urban rainfall, wind circulation, number of fog days, relative humidity, etc. [27,28]. These have impact not only human health, but also materials and the management of built heritage. Although Tokyo has a strong heat island, there are potentials to mitigate this, through the urban greening of buildings or increasing the area of open water in central Tokyo [29,30]. Temperature increases and a decline in relative humidity alter the potential for mould growth and change insect life cycles. The total number of hours with above 30 ◦C are shown in Figure4. This will affect comfort within naturally ventilated buildings and put more pressure on the cooling systems in museum environments. It can also affect mould growth when accompanied by humid Atmosphere 2020, 11, 680 6 of 18 conditions, and will favour insect infestations. In Japan, the overwintering survival of insects has increasedheat stress along when with temperatures earlier appearances increase to in high the spring, values an from increase about in 28 the to number 32 °C [31]. of generations The northward each year,movement lengthening of insects of the through reproductive the Japanese season, archipel etc. However,ago has insects been canwidely also described. be susceptible The todistribution heat stress whenrange temperaturesof many insects increase have toincreased, high values including from aboutthose 28of todragonflies 32 ◦C[31]. [32] The and northward the Great movement Mormon ofbutterfly, insects Papilio through memnon the Japanese [33]. The archipelago southern green has been stink widely bug, Nezara described. viridula The has distribution moved away range from of manythe coasts insects to warmer have increased, regions [34]. including Looking those at paralle of dragonfliesls in other [32 cities,] and such the Greatas London, Mormon it is butterfly, possible Papilioto see a memnon notable[33 increase]. The southern in insects green such stink as the bug, webbingNezara clothes viridula moth,has moved Tineola away bisselliella from the [35], coasts which to warmermay be regionspartly [due34]. Lookingto climate at parallelschange, inbut other also cities, related such to as food London, availability, it is possible habitat to see and a notable urban increaseactivities in [36]. insects The suchchanges as the in webbinginsect populations clothes moth, can Tineolabe modelled bisselliella as a [function35], which of maythe future be partly climate due to[37,38]. climate Such change, changes but alsocreate related a characteristic to food availability, problem habitat with wood, and urban as a activitiesmaterial, [36which]. The is changesespecially in insectimportant populations in Japanese can be buildings. modelled asThe a functionextensive of use the futureof wood climate makes [37 ,38the]. Suchheritage changes particularly create a characteristicvulnerable to probleminsect infestation with wood, [39]. as In a material,Tokyo, the which urban is heat especially island important may cause in an Japanese increase buildings. in insect Thenumbers extensive and usevariety. of wood Additionally, makes the heritagethere is particularlyoften a greater vulnerable availability to insect of food infestation in cities, [39 and]. In insects Tokyo, thecan urbanbe transported heat island on may objects cause anor increasedisplay inmaterial insect numberss. Stag beetles and variety. are popular Additionally, as pets there in isJapan; often anotably, greater Dorcus availability spp. ofis foodan invasive in cities, insect and insectsfrom East can and be transported Southeast Asia, on objects which or can display be released materials. or Stagescape beetles [40]. are popular as pets in Japan; notably, Dorcus spp. is an invasive insect from East and Southeast Asia, which can be released or escape [40].

Figure 4. The total number of hours with temperatures above 30 ◦C averaged 2003–2007 over the Tokyo area. Note: Base map extracted from RealEstateJapan and JMA. Figure 4. The total number of hours with temperatures above 30 °C averaged 2003–2007 over the 3.2. Storms,Tokyo area. Typhoons Note: andBase Floods map extracted from RealEstateJapan and JMA.

3.2. Storms,Historic Typhoons floods in and Tokyo Floods are well described, for example in the great floods of 1742, the Zen monk Enju¯ was engaged in a pilgrimage and trapped by the intense rain, so left an account of damage to religious Historic floods in Tokyo are well described, for example in the great floods of 1742, the Zen buildings [41]. This historic event led the Sumida River to flood, eroding the piles of the Ryogoku¯ Bridge, monk Enjū was engaged in a pilgrimage and trapped by the intense rain, so left an account of as well as damaging Eitai and Shin’o¯ Bridges (Figure5a), while overflowing levees caused extensive damage to religious buildings [41]. This historic event led the Sumida River to flood, eroding the flooding in the Kasai district [42]. The Heavy Rain Event during July 2018 [43], although not affecting piles of the Ryōgoku Bridge, as well as damaging Eitai and Shin’ō Bridges (Figure 5a), while overflowing levees caused extensive flooding in the Kasai district [42]. The Heavy Rain Event during July 2018 [43], although not affecting Tokyo so strongly, caused tremendous damage elsewhere. There were 221 fatalities, 6296 buildings were completely destroyed, 8929 houses were inundated above the floor level, and two key buildings (National Treasures), 35 important cultural property buildings, and 24 registered cultural property buildings were affected [44].

Atmosphere 2020, 11, 680 6 of 16

Tokyo so strongly, caused tremendous damage elsewhere. There were 221 fatalities, 6296 buildings were completely destroyed, 8929 houses were inundated above the floor level, and two key buildings (National

AtmosphereTreasures), 2020 35, 11 important, 680 cultural property buildings, and 24 registered cultural property buildings7 were of 18 affected [44].

Figure 5. 5.(a ) Sudden(a) ShowerSudden OverShower Shin-Ohashi Over Bridge Shin-Ohashi and Atake byBridge Hiroshige and https: Atake//upload.wikimedia.org by Hiroshige/ https://upload.wikimedia.org/wikipedia/commonwikipedia/commons/c/cc/Hiroshige_Atake_sous_une_averse_soudaine.jpgs/c/cc/Hiroshige_Atake_sous_une_averse_soudain[ 45](b) Area of inundation e.jpgunder[45] flood conditions(b) Area of Tableof 1inundation. Source: (https: under//nlftp.mlit.go.jp flood /conditionsksj/index.html of[ 2 ]) (Tablec) Enlargement 1. Source: of the (https://nlftp.mlit.go.central area of the inundation.jp/ksj/index.html (d) Annual [2] mean) (c) seaEnlargement level anomalies of the for central Japan; source:area of Japanthe inundation. Meteorological (d) AnnualAgency). mean (e) Immersion sea level anomalies depth for thefor centralJapan; partssource: of Tokyo;Japan Meteorological sources: JPC 2018, Agency). The Nikkei (e) Immersion Shimbun, depth30 March for 2018,the central TBS News, parts 30 of March Tokyo; 2018. sources: JPC 2018, The Nikkei Shimbun, 30 March 2018, TBS News, 30 March 2018. Changes in rainfall patterns over Japan mean that rainfall is likely to increase more than 10% over the 21st century [46]. Over the period 1976–2012, the number of hours of heavy rain (>50 mm) have Changes in rainfall patterns over Japan mean that rainfall is likely to increase more than 10% increased across all regions of Japan, which is likely to continue into the future [47]. However, the picture over the 21st century [46]. Over the period 1976–2012, the number of hours of heavy rain (>50 mm) for Tokyo is not particularly clear, although it was noted some decades ago that the urban heat island have increased across all regions of Japan, which is likely to continue into the future [47]. However, enhances convective storm activity over the city [48]. There was a period with many hours of heavy the picture for Tokyo is not particularly clear, although it was noted some decades ago that the precipitation during the 1940s, though the 1990s seem to lie within the range of variation for the urban heat island enhances convective storm activity over the city [48]. There was a period with 20th century [49]. Nevertheless, the general view remains that there will be an increase in falls of many hours of heavy precipitation during the 1940s, though the 1990s seem to lie within the range heavy rain over the coming century [39]. In addition, there has been considerable public concern over of variation for the 20th century [49]. Nevertheless, the general view remains that there will be an increased frequency of stormwater flooding and its impact on residential housing [50]. Oddly, despite increase in falls of heavy rain over the coming century [39]. In addition, there has been considerable increases in total precipitation amount, the number of dry days with daily precipitation less than public concern over increased frequency of stormwater flooding and its impact on residential housing [50]. Oddly, despite increases in total precipitation amount, the number of dry days with daily precipitation less than 1mm is expected to increase in almost every region of Japan. In Tokyo, a declining water table or soil moisture has the potential to expose sensitive buried archaeological sites or weaken the foundations of buildings. The GIS mapping shows the potential risk to historic sites and museums. It reveals a high flood risk along the river and the presence of a large area of eastern Tokyo where land has

Atmosphere 2020, 11, 680 7 of 16

1mm is expected to increase in almost every region of Japan. In Tokyo, a declining water table or soil moisture has the potential to expose sensitive buried archaeological sites or weaken the foundations of buildings. The GIS mapping shows the potential risk to historic sites and museums. It reveals a high flood risk along the river and the presence of a large area of eastern Tokyo where land has elevations below mean tide level (Figure5b,c). Historic buildings such as the Sens o-ji¯ Temple complex and many museums will be flooded during infrequent but large storms and, in the future, vulnerability will probably increase more than previously thought under a changing climate. Figure5b,c show the extent of the inundation risk to museums and historic buildings. The risk is calculated adopting the conditions listed in Table2 for each important river in the catchment. The eastern part of Tokyo can be seriously affected, with about 15% of museums at risk from high water. Some 13 museums are likely to be affected when water levels rise 2.0–5.0 m (Table2). It is thus important to take measures to protect against flooding, especially that storage locations are required to be on upper floors, with water—and fire—proof doors. The collections in art museums are especially sensitive to damper environments. There are four art museums under threat from inundation, but three occupy galleries present on the 4th floor or above, so risk is much reduced. The Museum of Contemporary Art Tokyo and the Tokyo Metropolitan Archives are sensitive to flooding. There are 12 historic buildings in Tokyo at risk of inundation, such as Asakusa Shrine and Senso-ji¯ Niten-mon (Table1), so mitigation measures are especially relevant. Longer periods of inundation can cause more damage to museums and historic buildings through a range of secondary hazards, such as mould growth and insect attack. Saraswat et al. [51] present an overview of stormwater runoff management in Tokyo to guide optimal measures and management policies within the city’s governance. An increase in the future sea level (Figure5d) would also make Tokyo vulnerable and may cause sea defences in Tokyo Bay to fail by the end of the 21st century, with increased typhoon intensity adding further threat [13]. Modelling suggests that the frequency of typhoon landfalls will decrease (Figure6a) and the mean value of the typhoon central atmospheric pressure will not change significantly. An important point is that the arrival probability of stronger typhoons will increase (bottom right Figure6b) under future climate scenarios [52]. This means that flooding is a likely outcome of such increasingly intense falls of rain. Wind speeds in Tokyo in the future (2075–2099) are compared with those of the recent past (1979–2003) in Figure6b, suggesting that the probabilities of the occurrence of higher annual 1 maximum wind speeds will increase (i.e., exceeding 30 m s− ), while medians of the annual maximum wind speeds decrease [53]. Figure6c shows the relative typhoon wind risk in Japan, as the number of buildings likely to be damaged each year under the current and projected future climates. The decrease in frequency is associated with a decline in relevant typhoon events in Japan and although there is an increase in typhoon intensity, it is not enough to compensate for this decrease [53]. Dangers of wind Atmospheredamage 2020 in typhoons, 11, 680 across East Asia have recently been examined along with factors that aff10ect of 18 the intensity of damage and its extent, along with the potential to mitigate future impact [54].

Figure 6. (a) Probable number of typhoons in Tokyo in 100 years from the stochastic typhoon model. Figure 6. (a) Probable number of typhoons in Tokyo in 100 years from the stochastic typhoon model. Dotted and solid lines indicate present and future projections, respectively; see also [13]. (b) Exceedance Dotted and solid lines indicate present and future projections, respectively; see also [13]. (b) probabilities for annual maximum wind speeds in Tokyo under current and projected climate. Exceedance probabilities for annual maximum wind speeds in Tokyo under current and projected (c) Percentage wing risk for residential buildings in Japan under current and future scenarios [53]. climate. (c) Percentage wing risk for residential buildings in Japan under current and future scenarios [53].

3.3. Earthquakes and Fires Japan is frequently affected by devastating earthquakes, because of the active seismicity caused by the subduction of the Philippine Sea Plate beneath the continental Eurasian Plate and Okinawa Plate, as well as dense distribution of inland active faults. There were major earthquakes in Tokyo in 1703 (Genroku earthquake), 1855 (Ansei Edo Earthquake) and 1894 (Meiji Tokyo Earthquake) [55], but it is the Great Kantō Earthquake of 1923 that has been especially influential (Figure 7a). It was so powerful that the 100-ton Great Buddha statue in Kamakura moved almost 60 cm. In the metropolis, the earthquakes often led to fires if they struck at lunchtime, when many people were cooking meals. Today, fires are more often caused by the rupture of gas pipelines and collapse of electricity pylons. However, at the same time, energizing fire is typical on the occasion of earthquake as it happened in the Great Hanshin-Awaji Earthquake in 1995. Extensive coastal reclamation has raised the risk of soil liquefaction during earthquakes, which are so frequent in Japan. Additionally, soil moisture and the water table are likely to affect the supporting structures of older buildings.

Figure 7. (a) Photograph of devastation in the area around Sensō-ji Temple, Asakusa after the Great Kantō earthquake of 1923, with smoke from fires in the background. Source: Public Domain File: Theosakamainichi-earthquakepictorialedition-1923-page9-crop.jpg [56] (b) The map of combined earthquake risks for Tokyo. Source: TMG 2018 and National Land Numerical Information (https://nlftp.mlit.go.jp/[2]).

Figure 7b maps the potential risk to buildings from earthquakes [57]. Although it is not tuned to heritage related structures, these sites are marked on the combined risk map of Tokyo. This combination brings together the risk of building collapse with the risk of fire. Older buildings tend

Atmosphere 2020, 11, 680 8 of 16

Table 1. Design storms (i.e., a hypothetical discrete rainstorm) characterized by a specific duration in each river. Note full details in MLIT 2020.

Target River Design Storm Rainfall Cities Affected Accounts for current development of river and drainage channels, regulating ponds, etc. Rise of September 1958 flood, Shibakawa River, New Shibakawa River after heavy rain Kanogawa Typhoon or Typhoon Adachi, Katsushika Shibakawa River that occurs every 100 years. Ida: 2 days rain 411 mm Inundation from overflow and collapse of levees. Inundation potential from the Chiyoda, Chuo, Shinjuku, Kandagawa River due to the Tokai September 2000 Tokai heavy Bunkyo, Taito, Shibuya, Kandagawa River heavy rain accounting for channel rainfall: rain 589 mm, hourly Nakano, Suginami, Toshima, maintenance. Depth from both maximum 114 mm Musashino, Mitaka river water and inside the levee. Account for current state of river Tonegawa River basin and channel and flood control. Tonegawa River upper Yattajima: 3 days rain Adachi, Katsushika, Edogawa Simulates expectation from heavy 318 mm rain once in 200 years. Simulates Edogawa River Upper Yattajima: 3 days rain Edogawa River overflow due to heavy rain that Adachi, Katsushika, Edogawa 318 mm occurs about once every 200 years. Accounts for current state of the Chiyoda, Chuo, Minato, Taito, Arakawa River river channel and Arakawa basin; 3 days rain Sumida, Koto, Kita, Arakawa, Arakawa River flood control. Simulates Arakawa 548 mm Itabashi, Adachi, Katsushika, River overflows due to heavy rain Edogawa every 200 years. Accounts for current state of channel and flood control. Nakagawa River, Simulates Nakagawa and Nakagawa and Ayase basins: Adachi, Katsushika Ayasegawa River Ayasegawa River overflows due 48 h rain 355 mm to 100-year heavy rain, but only inundation from Edogawa River. Ota, Setagaya, Hachioji, Accounts for current state of channel Tamagawa River basin and Tachikawa, Ome, Fuchu, Tamagawa River, and flood control. Simulates the upstream area of Ishihara Akishima, Chofu, Hino, Oogurigawa River Tamagawa River overflow due to a site: 2 days rain 457 mm Kunitachi, Fukuo, Komae, 200-year heavy rain. Tama, Inagi, Hamura, Akiruno Accounts for development of river Tamagawa River basin and channels. Simulates Asakawa Asakawa River the upstream area of Ishihara Hachioji, Hino, Tama River overflows due to a 200-year site: 2 days rain 457 mm heavy rain.

Table 2. Elevation of museums and sites in flood risk areas.

Elevation/m Museums Historic Buildings 0–0.5 4 3 0.5–1.0 10 1 1.0–2.0 8 2 2.0–5.0 13 5 >5.0 0 1

3.3. Earthquakes and Fires Japan is frequently affected by devastating earthquakes, because of the active seismicity caused by the subduction of the Philippine Sea Plate beneath the continental Eurasian Plate and Okinawa Plate, as well as dense distribution of inland active faults. There were major earthquakes in Tokyo in 1703 (Genroku earthquake), 1855 (Ansei Edo Earthquake) and 1894 (Meiji Tokyo Earthquake) [55], but it is the Great Kanto¯ Earthquake of 1923 that has been especially influential (Figure7a). It was so powerful that the 100-ton Great Buddha statue in Kamakura moved almost 60 cm. In the metropolis, the earthquakes often led to fires if they struck at lunchtime, when many people were cooking meals. Today, fires are more often caused by the rupture of gas pipelines and collapse of electricity pylons. However, at the same time, energizing fire is typical on the occasion of earthquake as it happened in Atmosphere 2020, 11, 680 10 of 18

Figure 6. (a) Probable number of typhoons in Tokyo in 100 years from the stochastic typhoon model. Dotted and solid lines indicate present and future projections, respectively; see also [13]. (b) Exceedance probabilities for annual maximum wind speeds in Tokyo under current and projected climate. (c) Percentage wing risk for residential buildings in Japan under current and future scenarios [53].

3.3. Earthquakes and Fires Japan is frequently affected by devastating earthquakes, because of the active seismicity caused by the subduction of the Philippine Sea Plate beneath the continental Eurasian Plate and Okinawa Plate, as well as dense distribution of inland active faults. There were major earthquakes in Tokyo in 1703 (Genroku earthquake), 1855 (Ansei Edo Earthquake) and 1894 (Meiji Tokyo Earthquake) [55], but it is the Great Kantō Earthquake of 1923 that has been especially influential (Figure 7a). It was so powerful that the 100-ton Great Buddha statue in Kamakura moved almost 60 cm. In the metropolis, the earthquakes often led to fires if they struck at lunchtime, when many people were cooking meals. Today, fires are more often caused by the rupture of gas pipelines and collapse of Atmosphereelectricity2020, 11pylons., 680 However, at the same time, energizing fire is typical on the9 of 16occasion of earthquake as it happened in the Great Hanshin-Awaji Earthquake in 1995. Extensive coastal reclamation has raised the risk of soil liquefaction during earthquakes, which are so frequent in the Great Hanshin-Awaji Earthquake in 1995. Extensive coastal reclamation has raised the risk of soil liquefactionJapan. Additionally, during earthquakes, soil moisture which areand so the frequent water in ta Japan.ble are Additionally, likely to affect soil moisturethe supporting and the structures waterof older table buildings. are likely to affect the supporting structures of older buildings.

Figure 7. (a) Photograph of devastation in the area around Senso-ji¯ Temple, Asakusa after the GreatFigure Kant 7.o¯ earthquake(a) Photograph of 1923, of devastation with smokefrom in the fires area in thearound background. Sensō-ji Source:Temple, Public Asakusa Domain after the Great File:Kant Theosakamainichi-earthquakepictorialedition-1923-page9-crop.jpgō earthquake of 1923, with smoke from fires in the background. [56](b) The Source: map of combinedPublic Domain File: earthquakeTheosakamainichi-earthquakepictorial risks for Tokyo. Source: TMG 2018edition-1923-page9-crop.jpg and National Land Numerical [56] Information(b) The map (https: of combined //nlftp.mlit.go.jpearthquake /risks[2]). for Tokyo. Source: TMG 2018 and National Land Numerical Information (https://nlftp.mlit.go.jp/[2]). Figure7b maps the potential risk to buildings from earthquakes [ 57]. Although it is not tuned to heritage related structures, these sites are marked on the combined risk map of Tokyo. This combination Figure 7b maps the potential risk to buildings from earthquakes [57]. Although it is not tuned brings together the risk of building collapse with the risk of fire. Older buildings tend to be found in the to heritage related structures, these sites are marked on the combined risk map of Tokyo. This historic downtown of Tokyo. Those along the Arakawa and Sumidagawa rivers offer lower earthquake resistance,combination as the brings structures together typically the have risk wooden of building or light-gauge collapse steel with frames. the risk Machiya, of fire. Arakawa-ku Older buildings tend is one of the worst affected areas in Tokyo, a district of densely packed wooden houses and narrow alleys, with little access for fire trucks. High risk areas are thus characterised by tightly packed buildings. Additionally, shaking can be amplified by ground characteristics, and valley and alluvial lowlands may lead to a higher risk. Fire risk is often enhanced in residential areas because of the wide use of open-flame appliances, and high density adds to the risk of fire spreading as these communities have fewer open spaces, such as parks and wide roads, which might act as fire breaks. Overall, such conditions are typical of historic areas where there is likely to be a high concentration of close-set older wooden structures (as mapped for central Tokyo in Figure8a), with low resistance to fire [57]. Thus, the vulnerability of built heritage is not surprising, because it is most frequently associated with the older historic districts. Tokyo has been subjected to many fires. The most notable one is the Great Fire of Meireki, which occurred in 1657. It is rumoured that the fire was started when a cursed kimono was set on fire on a very windy day [58]. The fire spread quickly through the city, because of strong winds from the northwest, which illustrates the role of climate conditions in large scale fires. The conflagration that followed the Great Kanto¯ Earthquake destroyed neighbourhoods and some significant sites, such as the Metropolitan Police Department building (Figure8b). Such characteristics of central Tokyo contributed to the enormous loss of historic buildings and residences from fires after incendiary bomb raids during World War II. Atmosphere 2020, 11, 680 11 of 18 to be found in the historic downtown of Tokyo. Those along the Arakawa and Sumidagawa rivers offer lower earthquake resistance, as the structures typically have wooden or light-gauge steel frames. Machiya, Arakawa-ku is one of the worst affected areas in Tokyo, a district of densely packed wooden houses and narrow alleys, with little access for fire trucks. High risk areas are thus characterised by tightly packed buildings. Additionally, shaking can be amplified by ground characteristics, and valley and alluvial lowlands may lead to a higher risk. Fire risk is often enhanced in residential areas because of the wide use of open-flame appliances, and high density adds to the risk of fire spreading as these communities have fewer open spaces, such as parks and wide roads, which might act as fire breaks. Overall, such conditions are typical of historic areas where there is likely to be a high concentration of close-set older wooden structures (as mapped for central Tokyo in Figure 8a), with low resistance to fire [58]. Thus, the vulnerability of built heritage is not surprising, because it is most frequently associated with the older historic districts. Tokyo has been subjected to many fires. The most notable one is the Great Fire of Meireki, which occurred in 1657. It is rumoured that the fire was started when a cursed kimono was set on fire on a very windy day [59]. The fire spread quickly through the city, because of strong winds from the northwest, which illustrates the role of climate conditions in large scale fires. The conflagration that followed the Great Kantō Earthquake destroyed neighbourhoods and some significant sites, such as the Metropolitan Police Department building (Figure 8b). Such characteristics of central Tokyo

Atmospherecontributed2020 to, 11 the, 680 enormous loss of historic buildings and residences from fires after incendiary10 of 16 bomb raids during World War II.

Figure 8. 8. (a()a )Fire Fire risk risk for for Tokyo. Tokyo. Source: Source: TMG TMG 2018 2018and National and National Land LandNumerical Numerical Information Information ((https://nlftp.mlit.go.jp/).https://nlftp.mlit.go.jp/). ((bb)) The The Metropolitan Metropolitan Police Police Department Department building building burning burning after after the Greatthe Great Kant o¯ KantEarthquake.ō Earthquake. Source: Source: Public Public Domain—File: Domain—File: Metropolitan Metropolitan Police OPoliceffice afterOffice Kanto afterEarthquake.jpg Kanto [59]. Earthquake.jpg [60] There is the potential for increased risk of fire both after earthquakes and that induced by lightning strikes. Shindo et al. [60] show that the number of lightning flashes per year over Japan and has There is the potential for increased risk of fire both after earthquakes and that induced by increased over the period 1992 to 2008. Additionally, Tokyo is likely to see enhanced convective lightning strikes. Shindo et al. [61] show that the number of lightning flashes per year over Japan storm activity in future, so an increased frequency of lightning strikes and fires might be expected. and has increased over the period 1992 to 2008. Additionally, Tokyo is likely to see enhanced The potential for climate change to lead to more lightning strikes can be countered by improved convective storm activity in future, so an increased frequency of lightning strikes and fires might be protection against lightning and incorporating fire-suppression devices in buildings. The fire at expected. The potential for climate change to lead to more lightning strikes can be countered by Notre-Dame de Paris on the evening of 15 April 2019 initiated many concerns in Japan, yet soon after, improved protection against lightning and incorporating fire-suppression devices in buildings. The there was a devastating fire at Okinawa’s Shuri Castle in 31 October 2019. It was followed almost fire at Notre-Dame de Paris on the evening of 15 April 2019 initiated many concerns in Japan, yet immediately by a fire on small thatched-roof huts at a car park in Ogi-machi, one of the components of soon after, there was a devastating fire at Okinawa’s Shuri Castle in 31 October 2019. It was a World Heritage property named Historic Villages of Shirakawa-go and Gokayama in Gifu Prefecture. followed almost immediately by a fire on small thatched-roof huts at a car park in Ogi-machi, one Wooden structures and thatched roofs are especially vulnerable, so have been of great concern for of the components of a World Heritage property named Historic Villages of Shirakawa-go and many hundreds of years, so Japan developed a range of approaches to limit the extent of damage Gokayama in Gifu Prefecture. Wooden structures and thatched roofs are especially vulnerable, so from fire [39]. These fires in 2019 encouraged expanded budgets for heritage protection in Japan, but have been of great concern for many hundreds of years, so Japan developed a range of approaches also more modest activities; e.g., the Tokyo Fire Department offers fire prevention guidance to Zoj¯ o-ji¯ to limit the extent of damage from fire [39]. These fires in 2019 encouraged expanded budgets for temple, a complex which has survived many fires since the early 17th century, even though many of its heritage protection in Japan, but also more modest activities; e.g., the Tokyo Fire Department offers components, such as the mausoleums of the Tokugawa Shoguns, were burnt down during raids of World War II.

3.4. Debris Flow, Slope Failure and Landslides A range of sediment disasters are induced by heavy rain, but also triggered by earthquakes. These can cause catastrophic damage to built heritage, and such sediment flows include:

1. Debris flow—soil and rock on a hillside or in a riverbed are washed after heavy or continuous 1 rain, which can reach 20–40 km hr− 2. Slope failure—abrupt slope collapse under the influence of a rain or an earthquake. This occurs so suddenly that people fail to escape when it occurs near a residential area and can lead to many fatalities. 3. Landslide—massive quantities of soil move slowly downslope under the influence of groundwater and gravity. The large soil mass means serious damage can occur, and once started, it is extremely difficult to stop.

Sediment hazards are more probable in the western parts of Tokyo, because of the mountainous geography and shown in Figure9 which shows the red and yellow risk areas. Atmosphere 2020, 11, 680 12 of 18

fire prevention guidance to Zōjō-ji temple, a complex which has survived many fires since the early 17th century, even though many of its components, such as the mausoleums of the Tokugawa Shoguns, were burnt down during raids of World War II.

3.4. Debris Flow, Slope Failure and Landslides A range of sediment disasters are induced by heavy rain, but also triggered by earthquakes. These can cause catastrophic damage to built heritage, and such sediment flows include: 1. Debris flow—soil and rock on a hillside or in a riverbed are washed after heavy or continuous rain, which can reach 20–40 km hr−1 2. Slope failure—abrupt slope collapse under the influence of a rain or an earthquake. This occurs so suddenly that people fail to escape when it occurs near a residential area and can lead to many fatalities. 3. Landslide—massive quantities of soil move slowly downslope under the influence of groundwater and gravity. The large soil mass means serious damage can occur, and once started, it is extremely difficult to stop. Sediment hazards are more probable in the western parts of Tokyo, because of the mountainous geography and shown in Figure 9 which shows the red and yellow risk areas. Atmosphere 2020, 11, 680 11 of 16

Figure 9. Sediment disaster map of the Tokyo area. Red Zone where slopes can collapse and damage buildings and threaten lives. Yellow Zone where steep slopes can collapse, risking injury or life. Source:Figure National9. Sediment Land disaster Numerical map Informationof the Tokyo ( https:area. //Rednlftp.mlit.go.jp Zone where /slopes[2]). can collapse and damage buildings and threaten lives. Yellow Zone where steep slopes can collapse, risking injury or life. Red Zone: Where steep slopes are likely to collapse, buildings are damaged; areas where there is a Source: National Land Numerical Information (https://nlftp.mlit.go.jp/[2]). risk of significant damage to the lives or physical health of residents. In Japan, a permit is required for specificRed Zone development: Where steep activities slopes and are structurallikely to collapse, regulation buildings for buildings. are damaged;Yellow Zone areas: Where where steep there slopesis a risk are of likely significant to collapse, damage risking to injurythe lives or life,or physical and when health the dangerof residents. is apparent, In Japan, a warning a permit and is evacuationrequired for system specific is todevelopment be in place. activities and structural regulation for buildings. YellowRed Zone and: yellowWhere zonessteep areslopes more are predominant likely to collapse, in western risking Tokyo, injury but or there life, are and many when popular the danger places is inapparent, the eastern a warning and central and evacuation districts such system as the is NHKto be in Museum place. of Broadcasting and the Itabashi Art Museum,Red whichand yellow even thoughzones are not more in red predominant or yellow zones, in western there may Tokyo, be some but riskthere as are the sitesmany are popular close toplaces potential in the sediment eastern threats. and central districts such as the NHK Museum of Broadcasting and the ItabashiThere Art are Museum, nine museums which in even the yellowthough zone:not in seven red or are yellow in the zones, western there area may and be two some in the risk eastern as the partsites of are Tokyo. close to Additionally, potential sediment there are threats. two historic buildings in yellow zone: one is in the western area andThere the are other nine in themuseums eastern in part the of yellow Tokyo. zone: The west seven has are fewer in the historic western buildings area and and museumstwo in the thaneastern the east,part butof Tokyo. still there Additionally, are many small there red are and two yellow historic zones buildings liable to in sediment yellow zone: disaster one in is central in the Tokyo. This means that the risk is not only to the western part, but also the eastern, where there are relatively fewer sites likely to be threatened. In the west, which is more mountainous, the yellow zone is occupied by: Okutama Water and Green Friendship Hall, Gyokudo Art Museum, Ome Kimono Museum, Yoshikawa Eiji Museum, Ome Municipal Museum of Provincial History, Akiruno City Itsukaichi Museum and the Hamurashi Kyodo Museum. Protection can best take the form of slope maintenance, well-practiced in Hong Kong [61], which has steep terrain and receives heavy falls of rain, especially during typhoons.

3.5. Visitor Experience Under a Changing Climate As shown in Figure3, many external parameters a ffect visitor choices. Typically, wet weather can discourage travelling round the city, but on the other hand it can mean a greater tendency to go indoors to shelter [62]. Many individuals appear to actively adjust their plans throughout the day in response to rain. However, for others, attendance depends upon prior weather forecasts of rain. The duration of a visit is also likely to increase during rainy periods [63]. However, in the hotter weather of the future, visitors may want to escape from the oppressive outdoor heat, especially to air-conditioned museum interiors. In historic dwellings where mechanical ventilation is not appropriate, the heat of the interiors may be such that visitors will be driven outside and away from the poor air movement among crowds of visitors. The change in visitor behaviour is obviously not simply a matter of the changing climate and must also consider changes to visitor types and different patterns of behaviour and expectations. Atmosphere 2020, 11, 680 13 of 18 western area and the other in the eastern part of Tokyo. The west has fewer historic buildings and museums than the east, but still there are many small red and yellow zones liable to sediment disaster in central Tokyo. This means that the risk is not only to the western part, but also the eastern, where there are relatively fewer sites likely to be threatened. In the west, which is more mountainous, the yellow zone is occupied by: Okutama Water and Green Friendship Hall, Gyokudo Art Museum, Ome Kimono Museum, Yoshikawa Eiji Museum, Ome Municipal Museum of Provincial History, Akiruno City Itsukaichi Museum and the Hamurashi Kyodo Museum. Protection can best take the form of slope maintenance, well-practiced in Hong Kong [62], which has steep terrain and receives heavy falls of rain, especially during typhoons.

3.5. Visitor Experience Under a Changing Climate As shown in Figure 3, many external parameters affect visitor choices. Typically, wet weather can discourage travelling round the city, but on the other hand it can mean a greater tendency to go indoors to shelter [63]. Many individuals appear to actively adjust their plans throughout the day in response to rain. However, for others, attendance depends upon prior weather forecasts of rain. The duration of a visit is also likely to increase during rainy periods [64]. However, in the hotter weather of the future, visitors may want to escape from the oppressive outdoor heat, especially to air-conditioned museum interiors. In historic dwellings where mechanical ventilation is not appropriate, the heat of the interiors may be such that visitors will be driven outside and away from the poor air movement among crowds of visitors. The change in visitor behaviour is obviously not simply a matter of the changing climate and must also consider changes to visitor types and Atmosphere 2020, 11, 680 12 of 16 different patterns of behaviour and expectations. Museums and historic buildings are increasingly broadening the range of visitors they attract, so it Museumsis no longer and the historic well-informed buildings tourist, are increasingly with guidebook broadening in hand. the Plans, range for of example visitors theyat the attract, UK’s soNational it is no Trust, longer aim the well-informedto welcome a tourist, wider withvariety guidebook of visitor in hand.types Plans,they categorise for example as: at (i) the active UK’s Nationalthinkers, Trust,(ii) live aim life to to welcome the full, a wider(iii) spontane varietyous of visitor characters, types they(iv) categoriseyoung experience as: (i) active seekers thinkers, and, (ii)among live lifegroups to the with full, children, (iii) spontaneous (v) the family characters, group, (iv)(vi) young kids first experience families, seekers and (vii) and, home among and groupsfamily with[65]. children,Encouraging (v) the these family new group, groups (vi) of kids visitors first will families, inevitably and (vii) change home the and way family the [heritage64]. Encouraging sites are theseexperienced new groups and used. of visitors We can will imagine inevitably that change the gentle the waytours the through heritage historic sites are rooms experienced may be andless used.important Wecan than imagine more active that the pursuits gentle and tours greater through usehistoric of the grounds rooms may and besurroundings. less important than more activeIn pursuits recent years, and greater the sunnier use of theurban grounds environmen and surroundings.ts have led to more oxidizing pollutants and meantIn that recent the years, surfaces the sunnier of buildings urban have environments taken on have a somewhat led to more warmer oxidizing tone pollutants [66]. In addition and meant to thatchemical the surfaces drivers, of shifting buildings colours have taken may on be a somewhata product warmerof biological tone [ 65growth.]. In addition As the to climate chemical changes, drivers, shiftingviewing coloursthe beauty may of be a snowy a product Tokyo, of biological reminiscent growth. of the As paintings the climate of Hiroshige, changes, viewingis likely to the be beauty more ofdifficult a snowy (Figure Tokyo, 10). reminiscent The changing of the seasons paintings have of influenced Hiroshige, the islikely viewing to be of morecherry difficult blossoms (Figure (sakura 10).) Theand changingthe autumn seasons leaves, have the influenced dates of thethese viewing activiti ofes cherry have blossomshad to shift (sakura as the) and warm the autumn seasons leaves, have thegrown dates longer of these [67]. activities have had to shift as the warm seasons have grown longer [66].

Figure 10. ((a)) Hiroshige’sHiroshige’s SnowSnow SceneScene at Kinryuzan Buddist Temple, Asakusa District (b) Annual Tokyo snowfall. The The line shows the 7-year ru runningnning mean. Note: Image Image is is part part of of TotoToto Yukimi Hakkei (8 Snow Scenes of the EasternEastern Metropolis):Metropolis): http:http://mercury.lcs.mit.edu/~jnc/pri//mercury.lcs.mit.edu/~{}jnc/printsnts/8snow.html/8snow.html [[68].67]. Data from WMO Station ID:47662 of JMA.

4. Discussion and Conclusions This study presents maps of some natural pressures on cultural heritage in Tokyo. Accardo et al. [4] claim maps of heritage risk to be useful, because they provide a “deeper and more concise knowledge of risk intensity than may be obtained by comparing the potential danger level of any single cultural property, based on the three static/structural, human impact, and environmental factors, with its state of conservation (vulnerability index) recorded”. It is easy to accept such thoughts, but the translation of maps into management policies is not trivial. Maps of potential risk are strategic, so they seem more useful to large organisations or government agencies. Such entities need to consider the broader picture and prioritise and compare risks over an extensive range of sites. Ultimately, they need to allocate limited resources among sites with competing, but necessary demands; and budgets are always tight. It is also possible that the maps can be of some value to a single museum or site, as they may hint at risks of which they are unaware, but often they will know many of the risks that confront them. In Italy, Istituto Superiore per la Conservazione ed il Restauro (High Institute for Conservation and Restoration) has developed a risk map named Carta del Rischio del Patrimonio Culturale (Risk map of Cultural Heritage) since the 1990s. It integrates the national inventory of cultural heritage and storage building of artistic objects such as museums, and hazard maps of natural/human-induced disasters, to utilise it for establishing restoration plans of cultural heritage by Soprintendenze, national authorities of cultural heritage in the regions of Italy. Risk maps can reveal the changes in climate and pressures from natural disasters. They can be open and provide information to stakeholders and the public. The risks may become evident to more individuals and encourage risk reduction. While it is possible to create overlapping maps with GIS, Atmosphere 2020, 11, 680 13 of 16 the availability of data is often limited with only a few of the desirable maps are available. For instance, Tokyo tsunami data have yet to be made available in a useful format, although the municipality webpage gives tsunami hazard maps. In a publicly available GIS form, they can more readily be used to identify and visualise built heritage hazards and sites at risk in an effective way. Risk management and assessment in general is relatively advanced in Japan, so there is a hazard map portal site (https://disaportal.gsi.go.jp/index.html[ 68]). In contrast, application of risk maps to cultural heritage protection from natural/human-induced disasters is not so frequent. National-scale risk maps are useful for policy making such as allocation of resources, but smaller-scale maps dealing with multiple disasters should be necessary for site managers and museum curators who take care of one or small numbers of site or museums. Up to now, disaster preparedness planning has used such material for establishing evacuation routes for visitors and objects, but less for planning mitigation strategies. Risk maps can also be useful in designing new museums by assessing risks in advance. A general problem in creating risk maps is that most of the publicly available data focusses on general built structures rather than built heritage, so it would be best to develop techniques that might tune it for that use. Historic buildings, especially, are more sensitive to hazards. In this study, museums and historic buildings designated as national treasures and important cultural properties have been considered, but it is also characteristic of large cities like Tokyo that there are many privately owned cultural properties, and they should also be stored safely. There are other areas worthy of future expansion, e.g., much of our knowledge of insects is related to those which are agricultural pests, rather than those that place heritage at risk. A better understanding of the life cycles of wood-boring insects in Japan would be useful. An understanding of natural hazards is well developed in Japan, and the science of climate change is nicely represented by the Japan Meteorological Agency, but there is only limited effort to tune this to a future heritage climatology. Similarly, a knowledge of air pollution, both indoors and out, has largely been concerned with the impact on human health. The example of Tokyo can be applied to other large cities, which often have rivers and similar characteristics, so some risks are shared. Cultural heritage is affected by climate change, as this alters the nature of many hazards. It is evident that more work is necessary to improve the health of our heritage.

Author Contributions: The following statements should be used “Conceptualization, P.B. and M.H. and Y.F.; methodology, M.H. and Y.F.; data analysis P.B.; investigation and writing P.B. and M.H. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Acknowledgments: We would like to thank Helen Lloyd of the UK National Trust for her usual thoughtful advice. Conflicts of Interest: The authors declare no conflict of interest.

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